To read Proto messages from API you have to follow these steps:
- Read the first four bytes, that's the message length, reverse the byte array, and change it to integer.
- Use the length and read that amount of bytes from the stream.
- Now you have the full message bytes, use Google Protocol Buffer SDK for your programming language to deserialize the message to ProtoMessage.
- Use the ProtoMessage payloadType field to find the actual message type, then deserialize the payload with Google Protocol Buffer SDK to that message type.
To write your proto message to the API stream follow these steps:
- Change the proto message object to the byte array by using Google Protocol Buffer SDK for your programming language.
- Get the length of the byte array, change it to byte array, reverse it
- Write the length + message byte array to the stream.
The system architecture is little-endian (that is, little end first), that's why we have to reverse the byte array before reading or writing.